This week's notes from the strange side of science features stories on why …

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Experimenting with nagging mothers: How's this for an experimental method: "Healthy controls and fully recovered participants with a past history of major depression were scanned while they heard praising, critical, and neutral comments from their own mothers." I would have loved to have seen how the university's human subjects committee responded to that proposal. Nevertheless, the research produced results. Both groups responded in an indistinguishable manner to neutral or complimentary remarks, but those with a past history of depression showed differences in neural activity when mom laid into them, even though they were otherwise free of symptoms.

Why our ethics don't always affect our purchases: This one falls under the general umbrella of explaining why our actions so rarely reflect our ethical standards. Almost everyone has some sort of product they object to on ethical grounds, such as factory-farmed meat, sweatshop clothing, or what have you. Just about everyone also ignores the ethical issues and buys some of it anyway. Some new research provides an explanation of why we seem to have a mixed history when it comes to considering our standards during purchases.

Faced with a product version of Survivor, subjects were asked to either pick a few items for further consideration or eliminate a few from the next round. It turns out that we're far more likely to listen to our ethics when we're eliminating a choice than when we're retaining one. The significance of the negative choices extends to our judging of others, as observers were more disturbed when someone eliminated an ethical choice than when they retained a nonethical one.

Crows watch us watching them: Or at least jackdaws, a type of corvid, do. Most corvids are very social animals, so researchers wondered whether they might use some of the same cues that humans and other primates do to register social information. So, they relied on a population of jackdaws that had grown familiar with some of their human handlers. When food was placed out in the open, the birds happily went to town if a familiar person stared at it, but displayed hesitancy if an unfamiliar person watched the food. In contrast, when food was hidden, they quickly found it when a familiar person stared at its location; this didn't work if the person was unfamiliar. To the authors, this suggests that the jackdaws had a concept of both social cues provided by visual attention, and of a social circle that created a cooperative environment.

Chickens do math: Another case of eerily intelligent birds. This is case of some clever experimental design. The authors managed to get newly hatched chicks to imprint on plastic spheres, which has an interesting consequence: apparently, when faced with collections of identical spheres, they'll head for the larger group. With the chicks properly trained, the authors then determined they could count by moving two sets of the spheres behind opaque screens as the chick watched. Once released, the chicks consistently headed for the screen that obscured the larger number of items. To test for math skills, the authors then started moving items between the screens as the chickens watched, and found that they still went to the location with more of the items.

No wonder they outlasted the dinosaurs.

Australia, land of the vicious meat ant: It's tempting to think of Australia as being filled with adorable marsupials, but nearly everything else on the continent—including the platypus—seems to be poisonous. Now, we can add another threat I wasn't previously aware of: there's a species there called a meat ant. For precisely the reason you might expect. I became aware of this because it turns out that they effectively kill cane toads. Apparently, said toads, not being native, had no expectation of being attacked by carnivorous ants, and responded in ways that were completely ineffective to their attack.

There's a pill for that, you know: If there was any doubt that kleptomania was an addiction like many others, a new study may put that to rest. In a double-blind, pill/placebo test, researchers have found that the drug naltrexone significantly reduces the behavior. Naltrexone's other uses? Control of alcohol and opiate addictions. It seems to work by limiting the pleasure addicts get from succumbing to their addiction.

Caffeine fuels a pain-free workout: There's one more reason to spend time with the espresso machine before doing, well, anything. It turns out that caffeine helps reduce the perception of muscle pain after a heavy workout. The best news: the effect was identical in both heavy consumers and caffeine neophytes.